Orthopedic implant with locking element

ABSTRACT

An orthopedic implant with a locking element for locking a bone screw in a bone screw receiving hole of the implant.

RELATED APPLICATIONS

This application is a continuation of application Ser. No. 13/610,281,filed Sep. 11, 2012, now U.S. Pat. No. 8,480,717; which is acontinuation of application Ser. No. 13/406,178, filed Feb. 27, 2012,now U.S. Pat. No. 8,262,708; which is a continuation of application Ser.No. 10/938,380, filed Sep. 11, 2004, now U.S. Pat. No. 8,123,788; whichis a continuation of application Ser. No. 10/802,906, filed Mar. 17,2004, now U.S. Pat. No. 8,048,075; which is a continuation ofapplication Ser. No. 10/098,991, filed Mar. 15, 2002, now U.S. Pat. No.7,077,844; which is a divisional of application Ser. No. 09/669,912,filed Sep. 26, 2000, now U.S. Pat. No. 6,383,186; which is a divisionalof application Ser. No. 09/022,344, filed Feb. 11, 1998, now U.S. Pat.No. 6,139,550; which claims the benefit of provisional application Ser.No. 60/037,139, filed Feb. 11, 1997; all of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to skeletal plate systems foraligning and maintaining bone portions of the same bone or of differentbones in a selected spatial relationship for healing or fusion of thebone portions, respectively. In particular, the present inventionrelates to skeletal plating systems comprising a plate that is flatand/or convex over a substantial portion of the lower surface of theplate along the longitudinal axis of the plate, bone screws, and locksfor locking the bone screws to the plate; to segmentable plates;crossing screw plates; and combination bone screw-lock-plate systemspermitting or causing, intersegmental bone compression and/orshortening.

2. Description of the Related Art

It is current practice in orthopedic surgery to use plating systems forjoining portions of a broken bone, or for fusion of portions of separatebones. Such systems are composed essentially of plates and screws foraligning and holding the bone portions in a desired position relative toone another. Plating systems have usefulness in the spine, and havegeneral skeletal use on the flat bones, such as the scapula and thepelvis by way of example, and for use on tubular bones, such as thehumerus, ulna, radius, femur, and tibia by way of example.

Problems associated with such plating systems have included hardwarebreakage, hardware loosening, inability to gain adequate fixation, anddistraction pseudoarthrosis where the plate will not allow the boneportions to come together over time resulting in a failure to get solidbone healing. These occurrences may cause problems, be associated withsurgical failure, and require further surgical procedures to repair thedamage, remove the failed hardware, and/or to reattempt skeletalstabilization.

Plates are usually provided to the surgeon for use in sets having arange of sizes so as to provide for such features as biologicalvariability in size, the numbers of segments to be joined, and thelength of the portions of bone to be joined. By way of example, it wouldbe common for a plating system for use on the anterior cervical spineand for joining from two to five vertebrae to comprise of from forty tosixty plates. This requires manufacturers to make a large number ofdifferent plates, resulting in increased manufacturing costs andinventory costs and increased costs for hospitals to stock large numbersof plates. Further, in the event that a plate is used and another of itskind is needed before it can be replaced, the ability to provide to apatient the best care could be compromised.

Known plating systems additionally experience problems in connectionwith those procedures where bone grafts are placed between vertebralbodies to achieve an interbody fusion which heals by a process called“creeping substitution”. In this process, dead bone at the interfacesbetween the graft and the adjacent vertebra is removed by the body, as aprelude to the new growth of bone forming cells and the deposition ofnew bone. While the plates allow for proper alignment of the vertebraeand their rigid fixation, they can therefore, at the same timeunfortunately, hold the vertebrae apart while the resorption phase ofthe creeping substitution process forms gaps in the bone at the fusionsite with the result that the desired fusion does not occur. Suchfailure in an attempted fusion is known as pseudoarthrosis. A similarphenomenon occurs at the interface of a fractured bone's fragments andis known as non-union. When such a failure occurs, the hardware itselfwill usually break or become loosened over time requiring furthersurgery to remove the broken hardware and to again attempt fusion orfracture repair.

Based on a consideration of the features of all of the known platingsystems, there remains a need for an improved plating system having thefollowing combination of features:

-   -   1) The plate and screws should be sufficiently strong to perform        their intended function without mechanical failure;    -   2) The hardware, and specifically the screws, should be capable        of achieving adequate purchase into the bone;    -   3) Means should be provided for locking each and every bone        screw to the plate, and the locking means should be of        sufficient size and strength to reliably perform its intended        functions;    -   4) Bone screw locking means should preferably be retainable by        the plate prior to bone screw insertion, or should be reliably        attachable to a driver to prevent any small parts from becoming        loose in the wound;    -   5) Bone screw orientation should be provided to create maximum        screw purchase into bone and high resistance from being        dislodged from the bone;    -   6) An improved and lower cost of production method for the        manufacturer of medical plates should be provided;    -   7) A plate system should be provided for use in various sizes of        patients which can be easily made to a selected length by a        surgeon to fit the desired application in order to substantially        reduce the number of plates required; and    -   8) Bone screw and plating system should be provided that prevent        holding apart of bone portions during the process of creeping        substitution and causes, or permits, or both causes and permits        the bone portions to move toward each other to permit and        promote the fusion or healing of the bone portions.

SUMMARY OF THE INVENTION

The present invention meets the above stated needs by providing variousembodiments which are combinable, and may all be utilizable in the sameplating system, such embodiments include (1) a skeletal plating systemcomprising a plate, that is flat over a substantial portion of its lowersurface along the longitudinal axis of the plate and/or that has a lowersurface that is convex curved along a substantial portion of thelongitudinal axis of the plate, bone screws, and locks for locking thebone screws to the plate for skeletal use; (2) a skeletal plating systemthat permits a pair of bone screws to be inserted into a bone portion ina crossed over orientation and locked in place to the plate; (3) asegmentable skeletal plating system constructed so as to be selected forlength by the surgeon; and (4) a combination screw-lock-plating systemcapable of allowing or urging bone portions together.

1. General Use Skeletal Plating-System

a. Multiple Lock System

The plating system of a first embodiment of the present inventioncomprises a general use skeletal plate having a bottom surface forplacement against bone portions, wherein a substantial portion of thebottom surface of the plate is either flat or convex along thelongitudinal axis of the plate. It is appreciated that a lesser portionof the lower surface of the plate may be otherwise shaped. The plate ofthe present invention has a plurality of bone screw receiving holeswhich extend through the plate, from the upper surface to the lowersurface. The plate and its component parts, may be made of any implantquality material suitable for this purpose and suitable for use in thehuman body, such as, but not limited to, titanium or its alloys. Theplate and/or the associated components may be made of a bioresorbablematerial and may comprise or be coated at least in part with fusionpromoting chemical substances, such as bone morphogenetic proteins andthe like.

Bone screws are each insertable into a respective bone screw receivinghole for attaching the plate to bone. A locking element, preferably, butnot necessarily, in the form of a screw, is engageable in the lockingscrew hole of the plate and has a head formed to lock at least two ofthe bone screws to the plate. In the preferred embodiment, the lockingelements are pre-installed prior to use by the surgeon in a manner so asto not impede installation of the bone screws into the bone screwreceiving holes.

As a result, the problems previously associated with the locking screwsof the type applied after the insertion of the bone screws, includingthe problems of instrumentation to position and deliver to the plate thelocking means, backing out, breakage, stripping and misthreadingassociated with the prior art more delicate locking screws resembling“watchmaker's parts”, are eliminated.

b. Single-Lock System

The plating system of the second embodiment of the present inventioncomprises a single-lock plate for skeletal use having a bottom surfacefor placement against bone portions, wherein a substantial portion ofthe bottom surface of the plate is either flat or convex along thelongitudinal axis of the plate. The single-lock plate has a lockingelement that fits within a bone screw receiving hole or into a recessoverlapping a bone screw receiving hole to lock a respective one of thebone screws in place. According to this second embodiment of theinvention, each of the bone screws is locked to the plate by means of anindividual locking element which covers at least a portion of the bonescrew. Since in the preferred embodiment of the single-lock plate, noother holes need be formed in the plate to attach the locking elementsto the plate, the plate remains quite strong, or alternatively can bemade thinner or narrower while keeping the requisite strength for theparticular application.

The locking elements can be in many forms to achieve their intendedpurpose, such as, but not limited to, screws, threaded caps, rivets, setscrews, projecting elements, and the like.

In common, neither the single-lock nor the multiple lock plating systemrequires that the head of the bone screw be hollow, as per some priorknown plating systems. It will be appreciated that bone screws areweakened when their heads or head and neck portions are hollow so as toaccommodate a second screw at least in part, if not wholly within.

2. Crossing Screw Plating System

In a further embodiment of the present invention, combinable inapplication with either the multiple lock or the single-lock systems andother novel features herein taught, a plate provides for the crossingover of the shafts of at least a pair of bone screws within a boneportion. A crossed orientation of the screws within the bone provides amore secure engagement of the plate to the bone to which it is to beapplied because longer screws may be used and because an area of bone iswedged and trapped between the screws as compared to plates which do notallow paired screws to cross. The use of further screws crossed and/ornot crossed in combination with the crossed screw pair can be utilizedto trap a still larger section of bone. The plate of the presentinvention may have multiple bone screw receiving bores (with fixedcentral longitudinal axes) in which the bores are oriented in astaggered configuration, such that the center points of each of thepaired bone screw hole receiving bores are on different transverse linesto permit at least a pair of bone screws to be inserted in acrossed-over configuration within a bone portion. Preferably, the screwbores have defined longitudinal axes in the transverse plane of theplate though the screws may be capable of a variation in positioning aswill subsequently be described. In the preferred embodiment, theincluded angle formed by the shafts of the crossed screws is between 25to 90 degrees. For spinal use, by way of example, the paired screws arestaggered, but are still alignable within the same vertebra so as to bediagonally crossed within that same vertebra and preferably crossedwithin the posterior two thirds of the vertebral body.

3. Segmentable Plating System

In a further embodiment of the present invention a segmentable platingsystem is disclosed combinable with the multiple lock and single-lockplating system and the crossing screw teaching, as well as combinablewith other novel features herein taught. The segmentable plating systemprovides a single plate, or a limited set of plates, for aligning andmaintaining bone portions in selected spatial relationship in which theplates are manufactured so as to be strong in use, but separable intoshorter lengths by the surgeon as needed, thereby eliminating the needto stock a multitude of plate lengths.

By way of example, for application in the spine, an embodiment of thesegmentable plating system of the present invention comprises a platethat is capable of spanning multiple segments of a cervical spine andhas predetermined separation zones. The separation zones may bepositioned in a segmentable plate such that when a portion of thesegmentable plate would be applied to the vertebrae, the remainingseparation zones in the plate, if any, would be supported by anunderlying vertebrae. In use, the surgeon would determine theappropriate plate length needed and if the length needed was less thanthe length of the provided plate, the surgeon would remove the unneededportion of the plate at the appropriate separation zone. By way ofexample, this procedure may be easily performed when the plate is madeof titanium or one of its alloys, as the properties of titanium are suchthat when the plate is bent and then returned to its original position,a clean separation is made at the bend. The parts of the segmentableplates that are being separated can be held to either side of theseparation zone to ensure that a precise separation is effected. Theseparation zones of the segmentable plate, by way of example, maycomprise of the plate being scored along its upper, lower, or both upperand lower surfaces. The depth of such scores being dependent on thethickness of the plate, and being sufficient to create surface notchingsand a path of least resistance for the plate separation, and yet oflimited depth and shape, so as to not weaken the plate so as to renderit less than sufficiently strong for its intended use.

By way of example, for application to the anterior aspect of thecervical spine four segmentable plates each having generally a similarlength for example sufficient to span five vertebrae (a length of from80 to 120 mm), and each having different spacings between pairs of bonescrew holes could comprise a complete set of plates allowing a surgeonto have all lengths and hole spacings needed to fuse from two to fivevertebrae. While the described plates may be separable into a multitudeof usable portions, because of regulatory issues involving theidentification of each implant with a distinct and singular implantidentification number for tracking purposes it may be desirable toconfigure the plates of the present invention such that each plate willyield only one usable portion, such as is taught in the presentinvention.

The segmentable plating system of the present invention also hasapplication in reconstructive surgery. For example, during repair of abroken eye socket, the segmentable plating system of the presentinvention can be used to align and maintain the broken bone portions incorrect spatial relationship. The curved characteristic of an eye socketwould require the plate used to repair the socket to match thecurvature. The segmentable plate of the present invention may be made ofa malleable metal, with the malleability of the plate being enhanced bythe segmentation of the plate, such that it can more easily be contouredby the surgeon to the appropriate curvature. The correct length of thesegmentable plate can also be easily obtained by the surgeon as alreadydescribed. It should be noted that if for example surgical titaniumalloy is selected for the plate material, then the separation zonesallow the plate to be more easily bent, but without separating. Thepresent invention makes a virtue of the material property of that alloyin that it may be bent without damage, but fails with surprisinglylittle force if first bent and then bent back. Back bending is thereforeonly done for plate separation and is not needed for contouring whichrequires only primary bending.

The ability to separate a plate into segments also provides significantadvantages in the manufacturing process. By way of example, in theprocess of investment casting, a process commonly used to produceplates. The investment casting cost of material is minor relative to thelabor involved in the casting process for the production of each plateregardless of size. It is far more economical to cast one eight inchlong plate, which is later separable into four two inch long plates,than to make four two inch castings. If machining is included inproduction, as from bare stock or stamping or casting, that work can beautomated, but the placing of the piece into the machine and securing it(fixturing) generally requires hands on attention, is time consuming,and is a potential manufacturing bottleneck. An eight inch long plateyielding four two inch plates potentially separable at the end by themachine doing the machining, may be fixtured only once. In contrast, theprior art method of manufacturing would require each of the four twoinch long plates to be fixtured separately, one at a time. Therefore,the manufacturer can cast one long segmentable plate which can then beseparated in the later manufacturing stages to yield multiple plates atan overall lower cost. Similarly, if the plate were in the alternativeto be manufactured by machining from solid stock, great labor could besaved by fixturing and securing a single long plate that is laterseparable into multiple plates rather than having to fixture and secureeach of those plates individually.

4. Combination Screw-Lock-Plating System Capable of IntersegmentableCompression and Shortening

In a further alternative embodiment combinable with both the single-lockand multiple lock plate designs, the crossed screw teaching, and thesegmentable plate teaching as well as other novel aspects of the presentinvention taught herein, three types of combination screw-lock-platesystems are taught, each capable of intersegmentable shortening and/orcompression. Each of the taught systems is designed to counteract andcompensate for the lack of contact between bone portions to be joinedthat may occur as a result of creeping substitution described above. Thepresent invention will allow the vertebrae to move toward an interposedbone graft, and each other if necessary, instead of keeping thevertebrae apart during the occurrence of the resorption phase of thecreeping substitution process. Unlike prior art “dynamic” and/orcompression plating systems, the present invention may allow for thepreservation and/or enhancement of lordosis while otherwise restrictingthe motion of the bone screws relative to the plate.

The three types of screw-plate-lock systems, which are themselvescombinable with one another, are as follows: (1) Passive Dynamic; (2)Self-Compressing; and (3) Active Dynamic and are described below.

a. Locked Passive Dynamic Plating System

As used in this description, the term “locked” means the screws arelocked to the plate and can not back out. The term “dynamic” means thescrew is capable of movement even though it is locked within the plateto allow bone portions to move closer together. The term “passive” meansmotion of the screw relative to the plate is allowed, but not caused.

The passive dynamic system allows a bone screw to move relative to theplate even after being locked to the plate when a force is presentedagainst the screw. This system does not cause screw movement, but onlyallows for movement of the screw to occur and thus is a “passive”system. In a preferred embodiment, motion of the screw relative to theplate is confined to but one direction, that direction permitting boneportions to move closer to one another along the longitudinal axis ofthe plate.

In the passive dynamic system, a plate having a screw hole passingthrough the top and bottom surfaces of the plate for receiving a bonescrew, may have a round opening at the top of the plate and may have abottom opening that is oblong-shaped with a length greater than thediameter of a bone screw shaft locatable the screw hole when in use. Thehead of the bone screw is secured to the plate against backing out andgenerally against significant linear motion with a locking element,while the shaft of the bone screw is capable of angular motion relativeto the plate. The oblong-shaped bottom opening of the screw hole allowsthe shaft of the bone screw to travel relative to the plate while thebone screw head rotates. The movement of the screw is greatest at thedistal end of the screw, allowing for differential shortening of thebone portions being joined. For example, if such a plating system isapplied to the anterior aspect of the cervical spine, lordosis (a convexcurvature forward of the aligned vertebrae of the neck when viewed fromthe side) is enhanced when said passive movement occurs.

b. Self-Compressing Locking Plate System

In the self-compressing system, as a bone screw undergoes finaltightening, or as it is being locked to the plate with a locking elementthe bone screw is forced to move in one allowed and desired direction.The bone screw can not move back once it is locked to the plate by thelocking element. A purpose of the self-compressing system is to providea fixed and locked angle of the bone screw relative to the plate forproviding compression of bone portions to be joined, such as for examplethe cervical vertebrae adjacent a disc space, with movement of the bonescrew as it is seated to the plate, producing compression and lordosis.

Unlike prior screw systems, the screws are only allowed to move in onedirection, that being the direction that would bring bone portions to bejoined closer together by angular motion, rather than to producetranslational motion of a screw as a whole, without angular change. Thisinduction of a compressive load across bone portions to be joined orfused, induces bone growth and when bone resorption occurs at theinterface of the bone portions to be joined, those bone portions areurged to move closer together, thus avoiding the formation of a gap soas to mitigate against non-union or pseudoarthrosis.

The self-compressing system may comprise a plate having a bone screwreceiving hole passing through the top and bottom surfaces of the platewith a top opening that is round and has a rounded seat. The bone screwreceiving hole has bottom opening that has a central longitudinal axisthat is offset from the central longitudinal axis of the top opening.The bone screw may have a partially rounded head which fits within theupper portion of the bone screw opening and permits movement of thescrew head within the top opening in order to provide the appropriateangle for the bone screw shaft with respect to the plate as the bonescrew shaft passes through the bottom opening.

Further it is known in the art that compressive forces across the bonefurther induce bone growth and formation and the present inventionteaches novel ways of maintaining bone to bone contact, compressiveloading, and even a means for enhancing and increasing the compressiveload. A further benefit of the present invention can be appreciated byway of example in regard to use of the present invention on the anteriorcervical spine for spinal fusion.

c. Active Dynamic Locking Plating System

In the active dynamic system, a pre-load force is applied to a bonescrew such that while the screw may undergo no added motion initially,there is a selective force applied to the screwhead and the screw iscapable of motion in only one direction, such that should resorptionoccur at the interfaces of the bone portions to be joined then the screwis not only free to move in that, and only that direction, but is alsourged to do so as it moves to relieve the preload force. Features ofthese systems may be combined with each other.

By way of example only and not limitation, a plating system may utilizebone screw holes that have a lower surface opening that is oblong andextends from the center aligned to the longitudinal axis of the bonescrew receiving bore in a direction for which screw motion is desired. Aloading means such as a Bellville washer, lock washer, or otherspringing means is employed to bear upon the screw head when the screwis locked within the plate from backing out. Such a system urges thebone portions together over time as resorption permits.

For any given use, (plate, screw, hole, and spring) it is simple todetermine correct resistance, that being an amount less than would breakthe bone to which the force is being applied. The Belville-type washercan have a tab which fits into a recess formed within the top opening ofthe screw hole in order to facilitate proper orientation of the washeror the washer or spring means can be other than round so as to bedirectionally orientable when placed within the top opening of the screwhole.

When features of these self compressing and active dynamic systems arecombined, such a system forces bone portions close upon tightening andthen both allows and urges such further motion, as resorption permitsover time. The bone screw will only move further in the pre-orienteddirection if there is space available and if there is an opposing forcepresent less than the pre-loaded force on the screw.

OBJECTS OF THE INVENTION

It is an object of the present invention to provide an improved platingsystem which has the above described features and which avoids many ofthe shortcomings of previously known systems.

It is another object of the present invention to provide a lockingmechanism where a plurality of bone screws used for attaching a plate toa bone portion can be easily and reliably locked in place at the sametime by a single operation, and wherein the locking mechanisms forlocking the bone screws may be pre-installed by the manufacturer priorto the insertion of the bone screws by the physician so that thephysician does not have to attach the locking mechanism to the plate asa separate procedure during the operation.

A further object of the invention is to provide plates which aretextured or otherwise treated to promote bone growth beneath the plate.

Yet another object of the invention is to provide a system in which thebone screws and locking mechanisms, when fully installed, have a lowprofile.

It is another object of the present invention to provide for a platingsystem which may be at least in part bioresorbable.

It is another object of the present invention to provide for a platingsystem comprising at least in part of bone ingrowth materials andsurfaces.

It is another object of the present invention to provide for a platingsystem comprising at least in part of bone growth promoting substances.

It is another object of the present invention to provide plates with animproved holding ability within the bone due to a locked screw to platecrossover configuration.

It is another object of the present invention to provide a lockedplating system capable of selected and specific screw motion so as toaccommodate shortening of the bones to be joined.

It is another object of the present invention is to provide means forpreventing distraction pseudoarthrosis of the anterior cervical spine,while providing for cervical lordosis.

The above and other objects and features of the invention will becomemore readily apparent from the following description of preferredembodiments of the invention, provided with reference to theaccompanying drawings, which illustrate embodiments of the inventionsolely by way of non-limiting example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the first embodiment of a multiplelocking plate.

FIG. 2 is a top plan view of the multiple locking plate shown in FIG. 1.

FIG. 3 is a side view of the multiple locking plate shown in FIG. 1.

FIG. 4 is an end view of the multiple locking plate shown in FIG. 1.

FIG. 5 is a bottom view of the multiple locking plate shown in FIG. 1.

FIG. 6 is a top view of the multiple locking plate shown in FIGS. 1-5,with locking elements installed, in an open configuration.

FIG. 7 is a top view of a modification of a plate of FIGS. 1-6 with afour bone screw locking element in place.

FIG. 8 is a top view of a further embodiment of the multiple lockingplate of FIG. 1 with an elongated central slot for increased compressioncapability.

FIG. 9 is a locking element capable of use with the plates of FIGS. 1-6.

FIG. 10 is a top view of a locking element for use with the centralopening of the plate of FIGS. 7 and 22.

FIG. 11 is a top view of a locking cap for use in the end openings shownin FIGS. 1, 6 and 7.

FIG. 12 is a side view of the locking element of FIG. 16.

FIG. 13 is a side view of another embodiment of the locking element ofFIG. 16.

FIG. 14 is a perspective view of an alternative embodiment of cervicalspine locking plate using locking rivets.

FIG. 15 is a bottom view of the multiple locking plate of FIG. 14.

FIG. 16 is a top view of a preinstallable two bone screw lockingelement.

FIG. 17 is a top view of an alternative embodiment of a four bone screwlocking element having head slots for increased flexibility of thelocking tabs.

FIG. 18 is a bottom view of the rivet type locking element for use withthe central opening of the plate of FIG. 14.

FIG. 19 is a side view of a rivet locking element.

FIG. 20 is a top perspective view of the bottom portion of the head ofrivet of FIG. 19 viewed along lines 20-20.

FIG. 21 is a top perspective view of the head portion of a three bonescrew locking element.

FIG. 22 is a perspective view of a multiple locking plate formed toutilize locking elements in the form of threaded caps.

FIG. 23 is a side view of a locking element for use with the plate ofFIG. 22.

FIG. 24 is a side view of a bone screw.

FIG. 25 is a side view of an alternative form of a bone screw.

FIG. 26 is a bottom view of the bone screws shown in FIG. 24.

FIG. 27 is a top view of the bone screw shown in FIG. 24.

FIG. 28 is a top perspective view of a fourth embodiment of a multiplelocking plate.

FIG. 29 is a perspective view of locking element for use with the plateof FIG. 28.

FIG. 30A is a partial side sectional view of the plate of FIG. 28 alonglines 30-30 with a bone screw in place.

FIG. 30B is an alternative embodiment of the bone screw of the presentinvention.

FIGS. 31A-31E illustrates top plan views of alternative embodiments ofthe multiple locking elements of the present invention.

FIG. 32A is an elevational, cross-sectional detail view of a portion ofthe bone forming device engaged to a portion of the plate of the presentinvention.

FIG. 32B is an alternative embodiment showing a cross-sectional viewthrough the plate with a drill guide to guide a hole forming instrument.

FIG. 32C is an elevational, cross-sectional detail view of a portion ofan alternative embodiment of a bone forming device engaged to a portionof the plate of the present invention.

FIG. 32D is a cross-sectional view along line 32D-32D of FIG. 32C.

FIG. 33 is a perspective view showing the locking of the bone screws tothe plate.

FIG. 34A is a partial side sectional view of a shielded locking elementattached to a driver instrument.

FIG. 34B is a partial side sectional view of an alternative embodimentof a locking element.

FIG. 35 is a partial side sectional view of another embodiment of thelocking element.

FIG. 36 is a partial cross-sectional view showing a plate, lockingelement and bone screws along lines 36-36 of FIG. 33.

FIG. 37 is an enlarged portion of detail along line 37 of FIG. 36.

FIG. 38 is a side partial cross sectional view of a plate holderattached to a plate.

FIG. 39A is a side partial cross sectional view of another embodiment ofa plate holder attached to a plate.

FIG. 39B is a side partial cross sectional view of another embodiment ofa plate holder attached to a plate.

FIG. 39C is an end view of the plate holder shown in FIG. 39B.

FIG. 39D is an enlarged fragmentation view of the tip of the plateholder shown in FIG. 39B.

FIG. 40 is a top perspective view of an embodiment of a single lockingplate.

FIG. 41 is a top plan view of the plate shown in FIG. 40.

FIG. 42 is a side view of the plate shown in FIG. 40.

FIG. 43 is an end view of the plate shown in FIG. 40.

FIG. 44 is a bottom plan view of the plate shown in FIG. 40.

FIG. 45 is a top plan view of the plate shown in FIG. 40, with lockingelements in place.

FIG. 46 is a side view of a bone screw used with the plate shown in FIG.40.

FIG. 47 is a top view of the bone screw shown in FIG. 46.

FIG. 48 is a bottom view of the bone screw of FIG. 46.

FIG. 49 is a top view of a locking cap for use with the single lockingplate of FIG. 40.

FIG. 50 is a side view of the locking cap shown in FIG. 49.

FIG. 51 is a bottom view of the locking cap shown in FIGS. 49 and 50.

FIG. 52 is a bottom perspective view of the locking cap of FIGS. 49-51.

FIG. 53 is a cutaway view of the hole forming instrument threaded to abone screw hole of a plate.

FIG. 54 is a perspective side sectional view of a drill and drill guidethreadably engaged to the plate for drilling the hole for insertion of abone screw.

FIG. 55 is a perspective view of a single locking plate installed alonga bone with locking caps installed in two bone screw receiving holes.

FIG. 56 is a partial cross sectional view of a locking cap engaged to adriver for installing the locking cap.

FIG. 57 is a partial cross sectional view of the plate, bone screws andlocking cap of FIG. 55.

FIG. 58 is an enlarged fragmentary view of area 58 of FIG. 57.

FIG. 59 is a perspective view of a second embodiment of a single lockingplate having individual locking elements to lock each bone screw.

FIG. 60 is a perspective view of a threaded locking element for use withthe single locking plate of FIG. 59.

FIG. 61 is a partial side sectional view of the plate of FIG. 59 viewedalong lines 73-73 with the locking element of FIG. 60 in place to hold abone screw, but not fully tightened.

FIG. 62 is a perspective view of an alternative locking element for usewith a first modification of the single locking plate of FIG. 59.

FIG. 63 is a side sectional view of the first modification of the plateof FIG. 59 with the locking element of FIG. 62.

FIG. 64 is a perspective view of an alternative locking element for usewith the first modification of the plate of FIG. 59.

FIG. 65 is a side sectional view of the first modification of the plateof FIG. 59 with the locking element of FIG. 64 in place.

FIG. 66 is a perspective view of another alternative locking element inthe form of a rivet for use with a second modification of the lockingplate of FIG. 59.

FIG. 67 is a partial side sectional detail view of the plate of FIG. 59modified to use a locking element of FIG. 66 shown in place.

FIG. 68 is a top plan view of a single-lock plate.

FIG. 69A is a top plan view of plate of a single-lock the presentinvention having a staggered screw hole pattern to provide crossing overof the bone screws into bone.

FIG. 69B is an alternative embodiment of the plate shown in FIG. 69A.

FIG. 70A is cross sectional view of a bone with the plate of FIG. 69A or69B engaged to the bone with two bone screws shown crossed over andpenetrating the bone in different planes.

FIGS. 70B-70D are end views of alternative embodiments of the plateshown in FIG. 70A.

FIG. 70E is a side elevational view of a plate in accordance with thepresent invention shown applied to a long bone.

FIG. 70F is an enlarged detailed view along line 70F of FIG. 70E.

FIG. 71 is a top plan view of a further embodiment of the multiplelocking plate for use in stabilizing multiple segments of the spine orportions of a long bone.

FIGS. 72A-72H are top plan view of various embodiments of multiplelocking plates of the present invention.

FIG. 73 is a top plan view of an alternative embodiment of the presentinvention in the form of a multiple locking segmentable plate shown in aseparated state.

FIG. 74 is a top plan view of an alternative embodiment of a multiplelocking segmentable plate of FIG. 73 shown in a separated state.

FIG. 75 is a top plan view of an alternative embodiment of a multiplelocking segmentable plate shown in an unseparated state.

FIG. 76 is a top plan view of an alternative embodiment of a multiplelocking segmentable plate shown in an unseparated state.

FIG. 77 is a top plan view of a portion of an alternative embodiment ofa multiple locking segmentable plate shown in an unseparated state.

FIG. 78 is a top plan view of an alternative embodiment of a multiplelocking segmentable plate shown in an unseparated state.

FIG. 79 is a top plan view of the multiple locking segmentable plate ofFIG. 78 shown in a separated state.

FIG. 80 is a top plan view of an alternative embodiment of the presentinvention in the form of a single-lock segmentable plate shown in anunseparated state.

FIG. 81 is a top plan view of the single-lock segmentable plate of FIG.80 shown in a separated state.

FIG. 82 is a partial side sectional view of a passive dynamicscrew-plate-lock system of the present invention.

FIG. 83 is a top plan view of an opening in the plate shown in FIG. 82.

FIG. 84 is a partial side sectional view of the passive dynamicscrew-plate-lock system of FIG. 82 indicating motion in response to aforce being applied to the screw in the direction of Arrow A.

FIG. 85 is a partial side sectional view of the self-compressingscrew-plate-lock system of the present invention with the lock partiallyinserted.

FIG. 86 is a partial side sectional view of the self-compressingscrew-plate-lock system of FIG. 85 in with the lock fully inserted andthe screw seated.

FIG. 87 is a top plan view and opening in the plate shown in FIG. 86.

FIG. 88 is a side sectional view of the opening in the plate shown inFIG. 87.

FIG. 89 is a partial side sectional view of an active dynamicscrew-plate-lock system of the present invention.

FIG. 90 is a top plan view of the opening in the plate shown in FIG. 89.

FIG. 91 is a top perspective view of the Belville type washer of theactive dynamic screw-plate-lock system of FIG. 89.

FIG. 92 is a partial side sectional view of the active dynamicscrew-plate-lock system of FIG. 82 with the lock further tightened andthe screw seated.

FIG. 93 is a top perspective view of an alternative embodiment of thewasher of FIG. 94 having a tab for insertion into a corresponding recessin the plate.

FIG. 94 is a partial side sectional view of the active dynamicscrew-plate-lock system of FIG. 93 with the lock fully inserted, thescrew seated, and the tab of the washer inserted into a correspondingrecess in the plate.

FIG. 95A is a side perspective view of an alternative embodiment of aplate in accordance with the present invention.

FIG. 95B is a top perspective view of the plate in FIG. 95A.

FIG. 95C is a bottom perspective view of the plate in FIG. 95A.

FIG. 96A is a side perspective view of an alternative embodiment of aplate in accordance with the present invention.

FIG. 96B is a top perspective view of the plate in FIG. 96A.

FIG. 96C is a bottom perspective view of the plate in FIG. 96A.

FIG. 97A is a side perspective view of an alternative embodiment of aplate in accordance with the present invention.

FIG. 97B is a top perspective view of the plate in FIG. 97A.

FIG. 97C is a bottom perspective view of the plate in FIG. 97B.

FIG. 97D is a bottom plan view of the plate in FIG. 97B.

DETAILED DESCRIPTION OF THE DRAWINGS

In a first embodiment of the present invention a plurality of bonescrews are locked to a plate with a pre-installed locking element. Thisis referred to as the multiple locking plate system. The multiplelocking plates will be described, then the locking elements for lockingthe bone screws to the plate, and then novel bone screws for use withthe plates of the present invention. In an alternative embodiment, asingle locking element locks a single bone screw to the plate and isreferred to as the single lock system.

It is appreciated that the features associated with each of theembodiments of the present invention are not limited to the particularembodiment for which the features are described and are combinable withfeatures described in association with all the embodiments of thepresent invention.

1. General Use Skeletal Plating-System

a. Multiple Locking Plate System

The preferred embodiment of the multiple locking plate 2 according tothe present invention is shown in FIGS. 1-5. Plate 2 has a generallyelongated form whose outline is generally rectangular. It is recognizedthat other shapes for plate 2 may be employed. Plate 2 has a bottomsurface 27 for placement against bone portions, wherein a substantialportion of bottom surface 27 is either flat or convex along thelongitudinal axis of the plate. Plate 2 is for general skeletal useother than in the anterior cervical spine.

As an example only, plate 2 is provided with three locking screw holes12, each of which in the preferred embodiment is internally threaded 3,and each of which is surrounded by a shallow countersunk region 14. Aswill be described in greater detail below, in the preferred embodiment,bone screws are inserted in the bone screw receiving holes and a singlelocking element associated with each of the locking screw holes 12 locksa number of bone screws 30 in position at one time. The locking elementmay be pre-installed to the plate.

In the embodiment illustrated in FIGS. 1-5, each end locking element 20will lock three bone screws 30 in place, while locking screw 21 incentral locking hole 12 locks two bone screws 30 in place. As shown inFIG. 7, central locking element 25 can also be configured so that fourbone screws 30 are locked at one time. Plate 2 may have a thicknessappropriate for the strength required for the bone or bones to which itis to be applied and generally in a range from 2 to 8 mm is preferred.

As shown in FIG. 5, at least a portion of bottom surface 27 of plate 2,preferably has a porous, and/or textured surface and may be coated with,impregnated with, or comprise of fusion promoting substances (such asbone morphogenetic proteins) so as to encourage the growth of bone alongthe underside of plate 2 from bone portion to bone portion. The texturedbottom surface 27 also provides a medium for retaining fusion promotingsubstances with which the bottom surface 27 layer can be impregnatedprior to installation. The bottom surface 27 of plate 2 may be given thedesired porous textured form by rough blasting or any other conventionaltechnology, such as etching, plasma spraying, sintering, and casting forexample. If porous so as to promote bone ingrowth, the bottom surface 27is formed to have a porosity or pore size in the order of 50-500microns, and preferably 100-300 microns. Bone growth promotingsubstances with which the porous, textured bottom surface 27 can beimpregnated include, but are not limited to, bone morphogeneticproteins, hydroxyapatite, or hydroxyapatite tricalcium phosphate. Theplate 2 may comprise of at least in part a resorbable material which canfurther be impregnated with a bone growth material so that as theresorbable material is resorbed by the body of the patient, the bonegrowth material is released, thus acting as a time release mechanism. Byhaving plate 2 itself made from a material that is resorbable and byhaving bone growth promoting material present permits the bone portionsto be joined to do so in a more natural manner as the plate becomesprogressively less load bearing thereby avoiding late stress shieldingof that bone area.

As further shown in FIGS. 4 and 5, at least one end of plate 2 may havea recess 18 that can cooperate with a compression apparatus.

FIG. 6 is a top plan view of plate 2 of FIG. 1 with locking elements 20,21 inserted. In the preferred embodiment the locking elements are in theform of screws that cooperate with the threaded interior 3 of thelocking holes 12. Each of these locking elements 20, 21 is shown in itsinitial open orientation, where the orientation of the cutouts 22 in thehead 23 of each locking element 20, 21 is oriented so as to permitintroduction of bone screws 30 into adjacent bone screw receiving holes6,8 without interference by the head 23 of the locking element 20, 21.

FIG. 8 is a top view of another embodiment of plate 2 of FIGS. 1-5, andis generally referred to as plate 120. Plate 120 is provided with alongitudinally extending elongated slot 122 along its longitudinal axiswhich is superimposed on the middle locking hole 12. Elongated slot 122allows additional relative movement between plate 120 and a compressionpost 54 associated with a compression tool during a compressionprocedure.

Referring to FIGS. 14 and 15, an alternative embodiment of a multiplelocking plate referred to by the number 70 is shown. In plate 70, ratherthan the threaded locking hole 12, a central opening 200 for receiving aremovable rivet 202, of the type shown in FIGS. 17-20, is provided. FIG.15 is a bottom view of the plate 70 shown in FIG. 14. The contour ofplate 70 is the same as that of plate 2 shown in FIGS. 1-5. The rivet202 is removable and fits within the unthreaded opening 200, comparableto the locking hole 12 and slot 122 described above. Other embodimentsmay employ a rivet that is not removable, but is manufactured as part ofplate 70 as would be used in the end locking holes 19 of FIGS. 14 and15.

Referring to FIG. 22, another alternative embodiment of a multiplelocking plate is shown and is generally referred to by the number 230.The plate 230 uses threaded caps, such as cap 300 shown in FIGS. 9 and23, for a locking element or preferably one with cut outs as describedherein having an appearance in a top view such as the locking screwelement in FIGS. 10-11, for example. The central locking hole 602 has anelongated slot 234 for providing an increased compression capability, ifdesired.

Referring to FIGS. 10-13, a first embodiment of locking elements 20, 21,and 25 in the form of locking screws according to the present inventionfor use with plate 2 are shown. FIG. 10 is a top plan view illustratingthe head 23 of the central locking element 25 shown in FIG. 7. The shaft46 of locking element 25 is threaded 47 to mate with the threading 3within the associated locking hole 12 of plate 2. As shown in FIG. 21,each segment 49 on each side of cutouts 22 of the locking element 21 hasa bearing surface 48 formed at the lower surface of locking element head23. As shown in FIG. 16, the locking element head 23 can be providedwith two slits 42 for providing flexibility to the locking element head23 to assist in the locking element's ability to ride over the top ofthe bone screw head 32 during the locking action when the lockingelement is rotated.

Referring to FIGS. 6 and 10-13, it will be appreciated that when thelocking elements 20, 21 are rotated in the clockwise direction withrespect to the view of FIG. 6, a respective bearing surface 48 will rideupon the curved top surface 39 of a respective bone screw head 32 inorder to positively lock the associated bone screws 30 and the lockingelements 20, 21 in place. This bearing feature can be used with theother locking elements described herein. Similarly, the bearing surfaceof the locking elements 20, 21, 25 can be also cammed.

Alternatively, as shown in FIGS. 12 and 13, in place of a flat bearingsurface 48, a ramp or wedge shaped surface 44 may be used to increasethe force applied to the bone screw head 32. In an alternativeembodiment cam design when locked, the leading end of the ramped portion44 of locking element 21 would be lower than the prominence of the bonescrew head 32 so that more force is needed to lift the locking element21 and untighten it than is needed for the locking element 21 to remaintight and locked. However, the locking element head 23 need not haveslits, be cammed or have a ramped surface to achieve the locking of bonescrew 30 in place. Pressure, friction, interference fits, or otherengagement means capable of preventing the locking element from movingfrom its locked position may be employed.

Referring to FIGS. 17-20 a rivet 202 intended for use in associationwith plate 70 of FIGS. 14-15, is shown and is also shown in detail incross section in FIGS. 19 and 20. Rivet 202 has a head 204, a shaft 206,and an elongated bottom segment 208 for fitting within the correspondingopening 200 in plate 70. The lower surface 210 of the head 204 of therivet 202 has a bearing surface, such as on the bottom of lockingelement 20, 21, for engaging the top surface 39 of the bone screw head32. For use in the end locking holes 19, the upper surface of theelongated bottom segment 208 can have a camming surface for cooperatingwith the camming surface 17 of the bottom of plate 70 to hold the rivet202 in the locked position against the bone screw head 32, as shown inFIG. 15. While the rivet of FIG. 18 is a separate, removable componentfrom the plate, the rivets, and particularly those for use with the endlocking holes, can be formed as part of the plate during themanufacturing process of the plate and rivet can be non removable if sodesired. The bearing surface of the rivet 202 may also be cam med toprevent the rivet from unlocking once the cammed portion passes over thescrew head.

Each of the above embodiments provides tight attachment of the lockingelement relative the bone screw 30 and relevant plate.

In the alternative embodiment of multiple locking plate 23 shown in FIG.22, the locking element can be in the form of threaded locking cap 300shown in FIG. 23. The threaded locking cap 300 has a thread 302 on itsouter circumference corresponding to the thread 303 on the innercircumference of the locking element depressions 304 in the top of plate230 shown in FIG. 22. The locking cap 300 is relatively thin,particularly compared to its width. The top 305 of locking cap 300 maybe provided with a noncircular recess or through hole 306 for receivinga similarly configured driving tool or employ other tool engaging means.

Referring to FIGS. 28, 29, and 30A another embodiment of the multiplelocking plate generally referred to by the number 400 and a lockingelement in the form of a thin locking member 412 are shown. Plate 400has an opening in its top surface for insertion of the thin lockingmember 412, a recess 402 associated with each of the bone screwreceiving holes 408 and a slot 410 in the side wall of the bone screwreceiving holes 408 to permit the thin locking member 412, having aseries of thin projections or blades 414, thinner than the slot 410,that give this locking member 412 an appearance similar to that of apropeller. The thin locking member 412 is able to be rotated within theplate so as to not cover the bone screw holes, thus allowing the thinlocking member 412 to be pre-installed prior to the installation of thebone screws by the surgeon. Limited rotation of the thin locking member412 allows the blades 414 to protrude through the slot 410 and to covera portion of the top of the associated bone screws 30. The blades 414 ofthe thin locking member 412 are flexible and, when rotated, slide overthe top surface 39 of the bone screw head 32 to lock the bone screw 30in place. As with the other embodiments discussed, each of theembodiments of the locking element is capable of locking more than onebone screw 30. It is appreciated that the various multiple lockingplates and locking element combinations are capable of locking as manyas four bone screws at once, but are equally effective for locking alesser number or none at all, that is securing itself to the plate.

It will be noted that one characteristic of each of the above describedlocking element embodiments is to have a driver engagement means, inthese cases for example, a recess 24 as large as the recess 34 in thebone screws 30 so that the same tool can be used to turn both the bonescrews 30 and the locking elements. Also, the locking elements aresufficiently strong and have sufficient mass so as to be able towithstand being locked without breakage.

Referring to FIG. 30B an alternative embodiment of the bone screw 30 ofthe present invention is shown. Bone screw 30′ is a variable angle screwhaving a head 32′ with a rounded top and has neck below the head 32′with relieved portions 33′a and 33′b to allow universal motion of thebone screw 30′ within the bone screw receiving hole of a plate as therelieved portions provide clearance for the screw to move. In oneembodiment, bone screw 30′ may be secured to the plate by a lockingelement that prevents the screw from backing out, but allows the lockingelement to bear down on the top of the screw head 32′ still moverelative to the plate. Alternatively, the bottom surface of the seat ofthe bone screw receiving hole and the bottom of the screw head 32′ maybe roughened to provide some resistance to movement of the screw head32′ within the bone screw receiving hole and/or the lock may bind thescrew head with sufficient force such that once the lock is tightened nomovement of the screw within the plate is possible.

The above-described examples of the multiple locking elements have anumber of cutout portions having an arc with a radius greater than thatof the bone screw head. However, it is appreciated that preinstallablemultiple locking elements can have a configuration without any cutoutportions and still permit for clearance of the bone screw head. Someexamples of such locking elements are shown in FIGS. 31A-31D in whichalternative embodiments of locking elements 20 a-20 d without cutoutportions and in which the bone screws can be installed into the bonescrew receiving hole 6 even when the locking element is pre-installed tothe plate. The locking elements may be rotated in the direction of arrowA to bear upon at least a portion of the screw head to lock the bonescrews to the plate.

In addition, the head 23 of each locking element 20, 21 is provided atits center with a noncircular recess 24, such as shown in FIG. 9 whichis engageable by an appropriate manipulation tool, such as shown inFIGS. 33-35. In the embodiment of head 23 shown in FIG. 9, theassociated tool would have a hex head, it is appreciated that othershapes of recesses in the head 23 may be used or other male or femaledriver engaging means may be used without departing from the scope ofthe present invention. The thread of each locking hole 12 and of eachlocking element 20, 21 has a close tolerance so that they will reliablyretain their orientations so as to permit introduction of bone screws 30into bone screw receiving holes 6, 8 without interference.Alternatively, the threads can be slightly mismatched or a thread orthreads can be made irregular or imperfect.

It is appreciated that while various forms of locking elements have beendisclosed, in light of the teaching, other equivalent means can be usedfor the purpose of locking the bone screws 30 in place. In FIG. 71, analternative multiple locking plate 990 is shown having additionalintermediate bone screw receiving holes 980 and, associated lockingelements 960 for locking the bone screws 30 in place.

In FIGS. 72A-72H various plates 700 a-h are shown. Each of these plates700 a-h have bone screws inserted through the bone screw receiving holes6 and then locked in place. As shown in FIGS. 72A-72H, one lockingelement 710, or two locking elements can be used to lock four bonescrews in place. In FIGS. 72A-72H, each of plates 700 a-h is shown withthe locking elements in their open orientation, before being rotated tolock the bone screws. Plates 700 a-700 h each have locking elements 710for locking bone screws inserted into bone screw receiving hole 6 of theplate.

FIG. 24 provides a side view of one embodiment of a bone screw 30according to the present invention. Bone screw 30 has a bone screw head32, a shaft 33, and a tip 36. FIG. 27 is a top view of the bone screw30. At the center of bone screw head 32 is a profiled recess 34 whichmay have the same form as the recess 24 of each locking element 20, 21in which case it may be turned with the same tool as that employed forturning locking elements 20, 21. It is appreciated that the driverengaging portion of the bone screw 30 could be slotted, and be eithermale or female.

In the embodiment of bone screw 30 shown in FIG. 24, the bone screw head32 is stepped, with the first lower head portion 35 being contiguouswith the screw shank 33 and has a smaller diameter than the upperportion of the bone screw head 32. Preferably, but without limitation,when this embodiment of bone screw 30 is employed, each bone screwreceiving hole 6, 8 of plate 2 has a countersunk region 14 matching thediameter of the upper portion of the bone screw head 32 and dimensionedfor an interference fit. The lower portion 35 of the bone screw head 32is dimensioned to achieve an interference fit with its associatedportion of bone screw receiving holes 6, 8. The larger diameter upperportion of bone screw head 32 assures that the bone screw 30 cannot beadvanced completely through bone screw receiving holes 6, 8 of plate 2.The bone screw 30 passes completely through the upper surface of plate 2without engaging the upper surface in any way.

As shown in FIG. 37, preferably, but without limitation, the head 32 ofscrew 30 passes unobstructed through the upper surface of the plateuntil the lower surface of enlarged screw head 32 engages the upper faceof the narrowed bone screw receiving portion at the midsubstance orbelow the midsubstance of the plate. This is considered optimal forallowing for the greatest screw to plate stability, even absent thelock, against all forces except those reverse the path of insertion,while still providing for the greatest plate strength beneath the bonescrew head 23. A sheer vertical circumferential wall is best able toconstrain the motion of a screw, if the head is similarly configured andthere is little tolerance between them. Placing the support of the headnear the mid thickness of the plate is preferred as it allows the upperhead to remain large to accommodate the recess for the driver withoutbeing weakened, while placing the support of the head away from theupper surface of the plate allows the screw head to be deep into theplate. Placing the support of the head at approximately the midthickness of the plate assures plenty of plate material beneath the headto support while providing adequate head length above and below thecontact point to prevent the contact point from acting as a fulcrum byproviding adequate lever arms to prevent unwanted motion.

In the alternative embodiment of bone screw 30′, as shown in FIG. 25,bone screw head 32′ is tapered in the direction from the top of the bonescrew head 32′ toward screw tip 36′. Again, the bone screw head 32′ isdimensioned to achieve an interference fit in the associated bone screwreceiving hole 6,8 when the bone screw 30′ has been fully installed.When this embodiment of bone screw 30′ is employed, bone screw receivingholes 6, 8 need not be provided with a countersunk region 14.

In each of the above embodiments of the bone screws, the bone screws 30and 30′ present a unique combination of a tapered screw shaft 33 and ahelical thread 31. The diameter of screw shaft 33 generally increasesfrom a distal portion of the shaft near the screw tip 36 toward proximalportion of the shaft near screw head 32. In the preferred embodiment,the rate of increase in diameter is also greater near the bone screwhead 32. Such a shape avoids stress risers and provides increasedstrength to the screw at the screw-plate junction, where it is neededthe most. The tapering of screw shaft 33 may have a concave form, asshown in FIG. 24, or may be linear. The distal portion of the screwshaft 33 may assume a constant diameter.

The thread 31 of the bone screw 30 has a substantially constant outer,or crest, diameter “d” from below the bone screw head 32 to near thebone screw tip 36. In the screw tip 36, the crest diameter of thread 31may be reduced for preferably one to two turns to facilitate theinsertion and penetration of the bone screw 30 into the bone.

In the preferred embodiment, the thread 31 of each bone screw 30 has anouter diameter slightly smaller than the diameter of the lowest portion35 of the bone screw head 32, which is adjacent the trailing, or upper,end of the associated thread 31. In addition, the thread 31 isrelatively thin, in the direction of the longitudinal axis of the screw,and tapers outwardly, and has a cross section of a triangle, though thesides need not be straight.

As shown in FIG. 38, plate holder 870 has a hollow tubular housing 872,with a central rod 874 having a thread 878 at one end for engaging oneof the threaded locking holes 12 in plate 2. The bottom end of thehousing 872 has projections 880, 882 that extend outwardly and thendownwardly to fit into the bone screw receiving holes 8 of plate 2preventing the housing 872 from rotating. The central rod 874 is locatedin the housing 872 such that it can be rotated by rotating a handle (notshown) which is fixed to the central rod 874 at its upper end.

In FIG. 39A an alternative embodiment of the plate holder 890 is shown.A single solid member 890 has a threaded projection 894 at its bottomend for attachment to the central threaded locking hole 12 in the plate.The bottom surface of the holder 890 of this embodiment is contoured soas to match the contours of the top surface of the plate adjacent to thelocking hole 12, shown as a depression 14.

Referring to FIG. 39B-39D, an alternative embodiment of the plate holder890′ is shown. Plate holder 890′ has a hollow tubular housing 872′having a handle 891′ at its top end and a bottom end 873′ configured forinsertion into a bone screw receiving holes 6 of a plate. A rod 874′having a sharp tip 875′ is contained within housing 872′ and is springbiased by a spring 875′. A lever 893′ is provided for advancing rod 874′from within housing 872′. Lever 893′ has a cammed portion 892′ to lockrod 874′ in position.

The bottom end of the housing 872 is slitted to form projections 880,881, 882, and 883′ that are moved outwardly by the shaft of rod 872′above tip 875′ in the direction indicated by arrow A when rod 874′ isadvanced from within housing 872′ to engage and lock into the bone screwreceiving holes 6 of plate 2 preventing the housing 872′ from separatingfrom plate 2. In this manner the plate holder 890′ functions as both aholder for a plate and also as a temporary plate fixation device to holdthe plate in the correct position to the bone prior to the insertion ofthe bone screws. Further, holder 890′ can be used to form pilot holesfor screw insertion into the bone portions.

Certain structural features of hole forming apparatus 60 are shown ingreater detail in FIG. 32A. In particular, it can be seen that thebottom end of housing 62 has a projecting portion 69 dimensioned to fitprecisely in a bone screw receiving hole 6 or 8 of plate 2. The bottom71 of the projecting portion 69 is flat in a plane perpendicular to theaxis of housing 62. When the projecting portion 69 of housing 62 issnugly inserted into a bone screw receiving hole 6, 8 and the flatbottom 71 is placed flush against the upper surface of plate 2, it isassured that the leading end 66 of shaft 64 will form a pilot hole inthe vertebral bone having an axis perpendicular to the plane of theassociated portion of plate 2, thereby assuring that the bone screw 30will be subsequently installed so that its axis is also perpendicular tothe plane which is parallel to the upper and lower surfaces of theassociated portion of plate 2.

When a plate is used which has a threaded bone screw receiving hole, thelower end of the pilot hole forming apparatus 60 is threaded so as toengage the thread in the bone screw receiving hole 6, 8 thereby fixingthe plate and the pilot hole forming apparatus together, assuring astable fit between the pilot hole forming apparatus and plate 2. Itshould be noted that the diameter of the leading end 66 of the shaft 64is small since it has to fit within the small space left between theinside wall of the pilot hole forming apparatus. Since it is only apilot hole for a self tapping bone screw 30 that is being formed, thesmall diameter is satisfactory.

Referring to FIG. 32B, if for any reason it should be desired to formthe pilot hole in the bone 50 by drilling, rather than by the use of thepilot hole forming apparatus 60, use can be made of a drill guide 80,having a lower end as shown in FIG. 32B. The drill 80 guide consists ofa tubular member 82 and a small diameter lower end 84 which isdimensioned to achieve a precise interference fit in the associated bonescrew receiving hole 6, 8 of plate 2. Along the small diameter lower end84, drill guide 80 has an axial end surface in a plane perpendicular tothe longitudinal axis of the drill guide 80 so that when the smalldiameter portion 84 is fitted into the bone screw receiving hole 6 andthe surface surrounding the small diameter portion 84 is flush againstthe upper surface of plate 2, the axis of the drill guiding bore 86 indrill guide 80 will be precisely perpendicular to the upper and lowersurfaces of the associated portion of plate 2. As with the casedescribed above, the bottom end of the drill guide 80 can be threaded soas to engage to the threaded opening of plate 2.

Referring to FIGS. 32C and 32D, an alternative embodiment of holeforming apparatus 60′ is shown. Hole forming apparatus 60′ is similar tohole forming apparatus 60, except that it has a ball end 62′ that fitswithin bone screw receiving hole 6. As shown in FIG. 32D, the ball end62′ may be oriented at any angle relative to the plate for angular holeformation into the bone. Hole forming apparatus 60′ provides forvariable angle preparation of the pilot holes for the bone screwsrelative to the plate.

After the bone screw receiving holes 6, 8 are formed in the bone 50through the upper two bone screw securing holes 6 of plate 2 by means ofeither hole forming apparatus 60 or drill guide 80, bone screws 30 arethreaded into the bone 50 while holding plate 2 firmly against the bone50 with plate holder 800.

FIG. 33 is a perspective view showing plate 2 of FIGS. 1-5, at a stageof a surgical procedure when bone screws 30 have been fully installed inbones or pieces of the same bone, and locking screws 20, 21 have beenrotated to lock three bone screws 30 in place; the left-hand lockingscrew 20 as viewed has been rotated through an angle of about 45° tolock three bone screws 30 in place and the central locking element 21has been rotated through an angle of about 90° to lock two other bonescrews 30 in place. At this time, one of the bearing surfaces 44 of eachlocking element 20, 21 rests atop the screw head 32 of a respective bonescrew 30. Ideally locking elements 20, 21 are provided to the useralmost fully tightened, but in the open position such that bone screwscan be inserted. Full locking of the bone screw requires 90° or less ofturning of the locking element and often 45° will suffice to lock thebone screws.

Installation of the multilock locking element 300 can also be performedwith a tool 220 such as shown in FIGS. 34A and 35 having a suitablyshaped tip 222 with a length corresponding to the depth of hole 306 in alocking cap 300. The end 222 of tool 220 is flared just proximal to themost distal end so that it creates a friction fit with the screw cap 300for ease of manipulation, and prevents the locking element 300 fromfalling off the tool 200. As shown in FIG. 34B, in the alternative, thetool receiving hole 306 can be flared to cooperatively engage a toolhaving a tip with a corresponding configuration.

FIG. 36 is a cross-sectional view in the plane of the center of the twoend locking screw holes 6 of plate 2, with two bone screws 30 in theirinstalled positions and locking element 21 in its locking position. FIG.37 is an enlarged view of one of the bone screws 30 in plate 2 of FIG.36. In a preferred embodiment, the axis of each screw 30 is generallyperpendicular to tangents to the upper and lower surfaces of plate 2 atpoints which are intersected by the longitudinal axis of the associatedbone screw 30. Thus, because of the curvature of plate 2 in the plane ofFIG. 36, bone screws 30 can be directed so as to converge toward oneanother at a desired angle. The axis of the two bone screws 30 shown inFIG. 36 may subtend an angle sufficient to cause the paths of bonescrews in the same plate to cross within the substance of the bone.Alternatively, the curvature of the plate from side to side may be so asto conform to the surface of the bone to which the plate is beingapplied and the axis of the paired screw hole may deviate from beingperpendicular to the plate when viewed on end to achieve the optimalconvergence.

Because the bone screws 30, once inserted, are locked to the plate, a“claw” of a rigid triangular frame structure is obtained at each pair ofbone screws 30 such that the attachment of plate 2 to the bone would behighly secure due to the trapping of a wedged mass of bone materialbetween the angled bone screws, even if any thread stripping shouldoccur. The “claw” may be further formed by three angled bone screws in atripod configuration or by four bone screws in a four sided clawconfiguration.

b. Single-Lock Plate Systems

Another embodiment of the present invention, the single locking platesystem will now be described. FIGS. 40-45 are views of a firstembodiment of a single locking plate system generally referred to by thenumeral 600. Plate 600 has the same contour as plate 2 shown in FIGS.1-5. Plate 600 has a bottom surface 27 for placement against boneportions, wherein a substantial portion of bottom surface 27 is eitherflat and/or convex along the longitudinal axis of the plate though alesser portion of bottom surface 27 may be otherwise configured. Asshown in FIG. 43, in another embodiment plate 600′ has a bottom surface627′ that is substantially flat along the transverse axis of plate 600′.

In a preferred embodiment, plate 600 contains bone screw receiving holes602 which are internally threaded 603 for receiving correspondinglocking elements in the form of a locking cap 610, shown in FIGS. 49-52.For example, in plate 600, the bone screw hole 602 may have an outerdiameter appropriate to the screw diameter appropriate to the bone(s)for which the plating system is to be applied. By way of example only,for use on a long bone such as the humerus, a bone screw of a diameterof 4.0 to 6.5 mm would be used and generally the screw head would beslightly larger in diameter. If a threaded locking cap were to be usedthen allowing for the space occupied by the cap is threads, the openingin the upper plate surface to receive the locking cap would be similarto generally 0.2 mm to 4.0 mm greater than the screw head size whichcould be 0.2 mm to 6 mm larger in diameter than the threaded shaftdiameter of the bone screw of approximately 5 mm with a preferred rangeof 4-6 mm though possibly greater. Cap attaching means other thanthreads may be used, such as bayonet type attachment elements.

The bottom of each bone screw receiving hole 602 of plate 600 has aninwardly stepped portion of properly selected dimensions for retainingan associated bone screw 170, as shown in FIGS. 46-48. As described ingreater detail below, in this embodiment, a single locking element inthe form of a locking cap 610 having threads 608 shown in FIGS. 49-52,is associated with each of the bone screws receiving holes 602.

The difference between the bone screw 170 used in the single lockingembodiment of the plate from the bone screw used in association with themultiple locking plate is essentially due to the fact that whereas inthe multiple locking plate embodiment the locking elements slide over aportion of the top 39 of the screw head 32 by a pressing, camming, orramp action, in the single locking embodiment the locking cap 610presses directly on the head 172 of the bone screw 170. Therefore, thehead 172 of the bone screw 170 of the present embodiment need not besmooth.

FIG. 55 shows two bone screws 170 and associated threaded locking caps610 in their fully installed positions. In these positions, headportions 174 and 176 of each bone screw 170 form an interference fitwith corresponding portions of an associated bone screw receiving hole602. Rim 612 of each threaded locking cap 610 forms an interference fitwith upper portion 178 of the head of its associated bone screw 170.Because the thread 608 of each locking cap 610 mates precisely with theinternal thread in an associated bone screw receiving hole 602, eachthreaded locking cap 610 is additionally subjected to a clamping forcebetween associated head portion 178 and the internal threads 603 ofassociated bone screw receiving hole 602. Preferably the rounded head614 of each threaded locking cap 610 assures that the upper surface ofan assembled plating system will be free of sharp edges, or projections.

FIG. 45 is a top plan view of the plate 600 partially installed, withthreaded locking caps 600 installed in bone screw receiving holes 602.

FIGS. 47-49 show a bone screw 170 for use with the single lockingplating system according to the invention. Bone screw 170 differs frombone screw 30 previously described in detail, only with regard to thestepped configuration of head 172. Preferably, bone screw 170 includes alower portion 174 which is contiguous with the screw shank and has areduced diameter equal to the maximum diameter of the shank 176. Portion178 of head 172 also has smaller diameter than lower portion 174. Thethread 182 has the same configuration as for the bone screw 30 discussedabove. However, either embodiment of bone screws can be used with any ofthe plates.

As in the case of the multiple locking plating system described above,the bone screws 170 for use in the single locking plating system arepreferably solid, where the screws adjoin the lower plate surface, whereas some screws used with prior art plates are hollow and are prone tobreakage, the only recess in the heads of the present invention screwsbeing for engagement of the tip 222 of driving tool 220 and with therecess being above the critical area of the lower plate surface screwjunction. Therefore, these bone screws 170 remain robust. The screwheads are not deeply slitted into portions as per some prior art screwsand the locking caps do not impose a radial outer force to expand thebone screw heads, so again the screw heads of the present invention arenot spread apart and stressed and weakened, and so remain robust. It isappreciated that variable angle screws 30′ shown in FIG. 30B may be usedin association with the single-lock plating system of the presentinvention.

Referring to FIGS. 59, 61 and 63 another alternative embodiment of theplate system of the present invention is shown and referred to by thenumber 500. The plate 500 may have any contour as any of the plates ofthe present invention appropriate for skeletal use and in which asubstantial portion of the lower surface of the plate is either flat orconvex along the longitudinal axis of the plate. Associated with each ofthe bone screw openings 502, are threaded openings 524 offset from thebone screw openings 502 for receiving the locking element 506, 508,shown in FIGS. 60 and 62 as a threaded locking set screw or cap 506 orscrew 508. Alternatively, locking element 506 may have a cutout portionwith a radius greater than the radius of a bone screw head as is shownin connection with locking element 508 in FIG. 64.

It is appreciated that other configurations of single locking plates maybe employed.

Referring to FIGS. 64-67 the heads 507 and 526 of the locking elements508 and 522 have a recess 510 and 524 corresponding to the radius of thebone screw openings 502 and 528 so that the locking element 508 and 522may be installed in place prior to the insertion of the bone screw 170into the bone screw receiving hole 502 and 528. When the lockingelements 508 and 522 are rotated, a portion of its head extends over thetop of the head of bone screw 170 to lock it in place. As with the aboveembodiments, the bottom surface of the locking screws 508 and 522 canhave a ramped, cammed, or other configuration for engagement with atleast a portion of the screw head.

Referring to FIG. 68, a locking plate 900 is shown in which there are anumber of bone screw receiving holes 950 along the longitudinal axis ofplate 900. With plate 900 of FIG. 68, the close spacing and increasednumber of bone screw receiving holes permits the surgeon to locateappropriate holes to be aligned with each of the bone portions to befixated, as well as allowing for more points of fixation to the bone.

2. Crossing Screw Plating System

Referring to FIG. 69A, an alternative embodiment of the plate of thepresent invention is shown and generally referred to by the numeral 960.The plate 960 has multiple bone screw receiving holes 970 passingthrough plate 960. The bone screw receiving holes 970 are spaced apartin a staggered configuration such that the center point of each of thebone screw receiving holes 970 are on transverse lines that are offsetfrom one another. The center point of the bone screw receiving holes 970are also offset from the midline of plate 970, but with lesslongitudinal distance between one another, while providing forsufficient distance between holes 970 to assure plate strength, thanplate 900 shown in FIG. 68.

Referring to FIG. 69B, an alternative embodiment of plate 960 is shownand generally referred to by the numeral 960′. Plate 960′ has the samestaggered pattern of bone screw holes 970 as plate 960 to permitcrossing over of two bone screws 30. In addition, plate 960′ has anoverall configuration suitable for use in the spine including theanterior cervical spine. For such use, an embodiment could have openings910 in lobed portions at the corner of plate 960′ and recesses 930 foruse with a compressing apparatus. Plate 960 could have additional pairsof lobes along the plate length. It is appreciated that the overallconfiguration of plate 960′ can vary as can the offset pattern of thebone screw holes.

As shown in FIG. 70A, the offset pattern of bone screw receiving holes970 permits longer bone screws 30 to be used than would otherwise bepossible if the screws were aligned in transverse pairs without havingbone screws 30 touch each other, due to the fact that the bone screws 30are in different planes, and each bone screw 30 gets to travel a muchlonger diagonal path in crossing the sagittal midline, providing greaterfixation.

In the preferred embodiment of plate 960, the shafts of two bone screws30 cross over in close proximity to each other and define an includedangle IA preferably between 25 to 90 degrees. Such a crossedconfiguration of bone screws 30 provides an extremely stable engagementof plate 960 to the bone as they are diagonally crossed within the samebone, thus trapping an area of bone between them.

For example, as shown in FIGS. 70B-70D, end views of alternativeembodiments of plate 960′ are shown wherein the bottom surface of theplate may be in the transverse plane relatively flat, curved, orotherwise configured to fit the surface configuration of the bone orbones to which the plate is to be applied. As shown in FIGS. 70E and70F, plates 960′ overall are generally shaped to conform to the bone(s)B to which they are applied.

3. Segmentable Plating System

Referring to FIG. 73, a further embodiment of the present invention inthe form of a segmentable plate generally referred to by the number 1000is shown in an separated state. Segmentable plate 1000 has an elongatedbody with a plurality of bone screw receiving holes 1010 spaced apartalong a substantial portion of the length of the segmentable plate 1000.Segmentable plate 1000 has a multiple locking system 1020 for lockingbone screws to plate 1010 as described above in connection withmulti-lock plate 2 shown in FIGS. 1-7. Plate 1000 is preferably, but notlimited to being made of a malleable material, such as titanium or oneof its surgically acceptable alloys.

Plate 1000 comprises a plurality of segments 1030-1038 which can beseparated from each other. A first segment 1030 of plate 1000 is markedby a segmentation zone 1040 along which the plate may be separated toseparate first segment 1030 from the remainder of plate 1000.Segmentation zone 1040 can be any type of scoring which creates a placeof least resistance along which when the plate 1000 is bent sufficientlyto create a separation in the material of plate 1000, the separationwill occur along the segmentation zone. By way of example only, in ananterior cervical plate having a thickness of 3 mm segmentation zone1040 may be formed by removing approximately 0.25 mm to 0.5 mm ofmaterial in total from the upper surface, lower surface or both upperand low plate surfaces combined of the plate. The scoring can berelatively thicker or thinner in width, variable in depth and ofvariable shape (e.g. “V” notched, rounded, etc.) to achieve the desiredqualities.

If plate 1000 is made of titanium, the inherent qualities of titaniumare such that the plate may be separated simply by bending the platesufficiently along segmentation zone 1040 while supporting the platewith appropriate plate holders to either side of segmentation zone 1040and then bending the plate towards its original position at which timethe plate will separate apart along the segmentation zone 1040,providing a sufficiently clean edge suitable for surgical use.

In use in the cervical spine as few as, only four different segmentableplates 1000 may be required to cover the wide range of differentlongitudinal spacing distances between bone screw receiving holes 1010for application to one to four levels of the cervical spine. Forexample, a set of four segmentable plates 1000 to cover the variouscombinations required for application to one to four levels of thecervical spine would include a first segmentable plate having a firstsegment with a spacing distance between the bone screw receiving holesof 10 mm, and subsequent segments similarly spaced at 10 mm intervalsbetween the holes; a second segmentable plate having a first segmentwith a spacing distance between the bone screw receiving holes of 12.5mm, and subsequent segments spaced at 12.5 mm intervals between thescrew holes; a third segmentable plate having a first segment with aspacing distance between the bone screw receiving holes of 15 mm andsubsequent segments spaced apart at 15 mm intervals between the holes;and a fourth segmentable plate having a first segment with a spacingdistance between the bone screw receiving holes of 17.5 mm andsubsequent segments spaced apart at 17.5 mm intervals between the holes.

The longitudinal spacing between the bone screw receiving holes 1010 maybe varied by changing the length of the portion of plate 1000 betweenbone screw receiving holes 1010 as illustrated by the dotted lines inFIG. 74.

While the described plates may be separable into a multitude of usableportions, as would be desirable for manufacturing purposes and possiblyfor clinical use, because of regulatory issues involving theidentification of each implant with a distinct and singular implantidentification number for tracking purposes it may be desirable toconfigure the plates of the present invention such that each plate willyield only one usable portion. In order to accomplish this goal, thesegmentation zone 1040 is made as shown in FIG. 79, such that theunused, separated pieces of the segmentable plates would not be usableas plates and would be discarded.

The ability to separate a plate into segments also provides significantadvantages in the manufacturing process. By way of example, in theprocess of investment casting, a process commonly used to produceplates, the cost of the material is not as significant as the laborinvolved in the manufacturing. Therefore, the manufacturer can cast onelong segmentable plate which can then be separated in the latermanufacturing stages to yield multiple plates at an overall lower cost.Similarly, if the plate were in the alternative to be manufactured bymachining from solid stock, great labor could be saved by fixturing andsecuring a single long plate that is later separable into multipleplates rather than having to fixture and secure each of those platesindividually.

Referring to FIGS. 75-79, various segmentable plates 1300-1700 are shownfor application in reconstructive surgery. Plates 1300-1700 have bonescrew receiving holes 1310-1710, locking elements 1320-1720, andseparation zones 1340-1740 respectively. For example, during repair of abroken eye socket, the segmentable plates 1300-1700 can be used to alignand maintain the broken bone portions in correct spatial relationship.The curved characteristics of an eye socket would require the plate usedto repair the socket to match the curvature. The segmentable plates1300-1700 are made of a malleable metal, the malleability of which isenhanced by the segmentation of the plate, and can be easily contouredby the surgeon to the appropriate curvature. The correct length of thesegmentable plate can also be easily be selected by the surgeon byseparating the plate at the appropriate segment as described above inconnection with plate 1000 shown in FIG. 73.

It should be noted that if for example surgical titanium alloy isselected for the plate material, then the separation zones allow theplate to be more easily bent, but without separating. The presentinvention makes a virtue of the material property of that alloy in thatit may be bent without damage, but fails with surprisingly little forceif first bent and then bent back. Back bending is therefore only donefor plate separation and is not needed for contouring which requiresonly primary bending.

Referring to FIGS. 80 and 81, alternative embodiments of the segmentableplate are shown and generally referred to by the numeral 1800 and 1900.Plates 1800-1900 having locking elements 1820 that are inserted intobone screw receiving holes 1810 and correspond to the single lock plateconfiguration described above in connection with FIGS. 40-49.Segmentable plates 1800-1900 may be segmented at segmentation zones 1840and 1940 as described above in connection with the multiple lockembodiment of the segmentation plate 1000.

4. Combination Screw-Lock-Plating System

a. Passive Dynamic

Referring to FIGS. 82-84 the passive dynamic system 2000 is shown havinga plate with a screw hole 2010 passing through the top and bottomsurfaces of the plate 2020 for receiving a bone screw 2030. The screwhole 2010 has a round opening 2040 at the top of the plate 2020 and anopening 2050 in the bottom of the plate that is in part coaxial with thetop opening 2040, but extends in one direction to form an oblong. Therounded head 2032 of bone screw 2030 is prevented from backing out ofplate 2020 with a locking element 2060 that is engaged to plate 2020,while the shaft of bone screw 2030 is capable of angular motion in thedirection of arrow A relative to plate 2020, since there is space in theoblong-shaped bottom opening 2040 of the screw hole 2010 for the shaftof the bone screw 2030 to travel in the one permitted direction relativeto the plate 2020.

The passive dynamic system allows bone screw 2030 to move relative toplate 2020 even after being locked to plate when a force is presentedagainst the screw. This system does not cause screw movement, but onlyallows for movement of the screw to occur and this is a “passive”system. Nevertheless, screw 2030 retains the ability to resist anyunwanted motion in all other directions. The use of variable screw 30′as already described may also allow for passive dynamic action, but isnot generally preferred as it does not limit the motion to but a singledirection.

b. Self-Compressing

Referring to FIGS. 85-88, a self-compressing system 2100 is showncomprising a plate 2120 having a bone screw receiving 2110 hole with atop opening 2140 that is preferably but not necessarily round, andhaving a rounded recessed portion 2142 is shown. The bone screwreceiving hole has bottom opening 2150 that is smaller in diameter thanthe top opening 2140 and has a central longitudinal axis 2153 that isoffset from the central longitudinal axis 2151 of the top opening 2140.The bone screw has a rounded head portion 2132 which fits within therounded bottom 2142 of the top opening 2140 and permits movement of thescrew head 2132 within the top opening in order to provide theappropriate angle A of the bone screw shaft with respect to the plate2120 as the bone screw shaft passes through the bottom opening 2150.

In the self-compressing system, as the bone screw 2130 is being lockedto the plate 2120 with a locking element 2160, the locking element 2160puts pressure on the bone screw head 2132 to make the bone screw 2130move in one direction. The bone screw 2130 cannot move back once it islocked to the plate 2120 by the locking element 2160. The purpose of theself-compressing system 2100 is to provide a fixed and locked angle A onthe bone screw 2130 for providing compression of bone portions.

c. Active Dynamic

Referring to FIGS. 89-92, the active dynamic system 2200 of the presentinvention is shown comprising a screw 2230 that is mounted to a plate2220 under a spring loaded force, such as with a Belville type washer2270 that applies a selected force to the screw 2230. The bone screw2230 will move in the direction of the force that is being applied asbottom opening 2250 of the bone screw receiving hole is oblong shaped.For example, the big end 2272 of the spring formed by washer 2270 bearsdown on the screw head 2232 away from the direction that the bone screw2230 is to be moved. For any given use, (plate, screw, hole, and spring)it is simple to determine correct resistance, that being an amount lessthan would separate the bone.

Referring to FIGS. 93-94, the washer 2270 may also have a tab 2290 whichfits into a recess 2292 formed within the top opening in order tofacilitate proper orientation of the washer when placed within theopening or alternatively the washer 2270 may have a non-circular shapeso as to not rotate when positioned.

In an active dynamic system, a pre-loaded force is applied to a bonescrew that keeps the screw in a certain orientation with respect to theplate. The bone screw will only move further in the pre-orienteddirection if there is space available and if there is no opposing forcepresent to counteract the pre-loaded force on the screw. These teachingsmay be readily and beneficially combined so as to for example form asystem that compresses on full screw seating, continues to urge the boneportions together, and can permit still further shortenings.

Referring to FIGS. 95A-95C, an alternative embodiment of a plate of thepresent invention is shown and generally referred to by the numeral3000. Plate 3000 has a bottom surface 3027 that is convex along asubstantial portion of the longitudinal axis of the plate and is concavealong the transverse axis of the plate 3000. Plate 3000 has asingle-locking element 3022 for locking a single bone screw 3030 toplate 3000.

Referring to FIGS. 96A-96C, an alternative embodiment of a plate of thepresent invention is shown and generally referred to by the numeral3100. Plate 3100 has a bottom surface that is flat along a substantialportion of the longitudinal axis of the plate and is concave along thetransverse axis of the plate. Plate 3100 has a multiple locking element3120 for locking two bone screws 3130 and single locking elements 3122for locking individual bone screws 3130 to plate 3100. Bone screwreceiving holes 3140 are staggered such that the center point of each ofthe bone screw receiving holes 3142 and 3144 are on transverse linesthat are offset from one another. The center point of the bone screwreceiving holes 970 are also offset from the midline of plate. Theshafts of two bone screws 30 cross over in close proximity to each otherand define an included angle IA between 25 to 90 degrees. Such a crossedconfiguration of bone screws 30 provides an extremely stable engagementof plate 960 to the bone as they are very close together and diagonallycrossed within the same bone, thus trapping an area of bone betweenthem.

Plate 3100 comprises a plurality of segments 3150-3156 which can beseparated from each other. A first segment 3150 of plate 3100 is markedby segmentation zones 3160-3164 along which the plate may be separatedto separate segments 3150, 3152, 3154, or 3156 from the remainder ofplate 3100. Segmentation zones 3160-3164 can be any type of scoringwhich creates a place of least resistance along which when the plate3100 is bent sufficiently to create a separation in the material ofplate 3100, the separation will occur along the segmentation zone.

It is appreciated that plate 3100 may include one or more of thescrew-lock-plating systems 2000, 2100, or 2200 described above in FIGS.82-84.

Referring to FIGS. 97A-97D, an alternative embodiment of a plate of thepresent invention is shown and generally referred to by the numeral3200. Plate 3200 has a bottom surface that is flat along a substantialportion of the longitudinal axis of the plate and is concave along thetransverse axis of the plate and has an upper surface that is concavealong the transverse axis of the plate 3200.

As shown in FIG. 97D, plate 3000 may include one or more of thescrew-lock-plating systems 2000, 2100, or 2200 described above in FIGS.82-94.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art thatchanges and modifications may be made without departing from thisinvention in its broader aspects and, therefore, the aim in the appendedclaims is to cover all such changes and modifications as fall within thetrue spirit and scope of this invention.

While specific innovative features may have been presented in referenceto specific examples, they are just examples, and it should beunderstood that various combinations of these innovative features beyondthose specifically shown are taught such that they may now be easilyalternatively combined and are hereby anticipated and claimed.

What is claimed is:
 1. An orthopedic implant for engaging at least onenon-vertebral bone of the human body, said implant comprising: a bodyhaving a first end, a second end, a length therebetween, and a widthperpendicular to the length, said body including a bone-contactingsurface along the length of said body, said bone-contacting surfaceconfigured to be placed against the at least one non-vertebral bone; atleast two bone screw receiving holes extending through said body from ascrew receiving side to a screw exit side proximate said bone-contactingsurface, each of said bone screw receiving holes having a centrallongitudinal axis extending therethrough from said screw receiving sideto said screw exit side, and being adapted to receive a bone screw forengaging said implant to the at least one non-vertebral bone, said eachof said bone screw receiving holes having a seat configured to contactsaid respective one of said at least two bone screws; at least two bonescrews each having a central longitudinal axis, each of said at leasttwo bone screws having a leading end for insertion through one of saidat least two bone screw receiving holes, respectively, and into the atleast one non-vertebral bone and a trailing end opposite said leadingend, said at least two bone screws each having a head and includingproximate said trailing end a contact surface area generally transverseto the central longitudinal axis and oriented toward said trailing endof said each of said at least two bone screws, respectively, saidgenerally transverse contact surface areas being formed on said heads,said heads each including a downward facing surface being configured tocontact said implant and oriented at least in part away from saidtrailing end of said each of said at least two bone screws,respectively, said heads each including a side surface between saidtrailing end and said downward facing surface of said each of said atleast two bone screws, said side surface being closer to said trailingend than said generally transverse contact surface area is to saidtrailing end; and at least one locking element, each of said at leastone locking element adapted to lock to said implant only said respectiveone of said at least two bone screws inserted in one of said at leasttwo bone screw receiving holes, said each of said at least one lockingelement contacting said generally transverse contact surface area andsaid side surface of said head of said respective one of said at leasttwo bone screws so as to retain said respective one of said at least twobone screws to said implant, said each of said at least one lockingelement having an outer perimeter contacting at least a portion of aperimeter of said one of said at least two bone screw receiving holeswhen said each of said at least one locking element contacts saidgenerally transverse contact surface area and said side surface of saidhead of said respective one of said at least two bone screws, said eachof said at least one locking element being removably coupled to saidimplant, said each of said at least one locking element having a roundinner surface adapted to contact said side surface of said head of saidrespective one of said at least two bone screws.
 2. The implant of claim1, wherein said each of said at least two bone screw receiving holes hasa side wall, said side wall having a groove configured to receive one ofsaid at least one locking element.
 3. The implant of claim 2, whereinsaid groove in said side wall of a first of said at least two bone screwreceiving holes encircles the entire perimeter of said first bone screwreceiving hole, and said groove in said side wall of a second of said atleast two bone screw receiving holes encircles the entire perimeter ofsaid second bone screw receiving hole.
 4. The implant of claim 1,wherein said head of said respective one of said at least two bonescrews has a round cross section through said side surface thereof andtransverse to the central longitudinal axis of said respective one ofsaid at least two bone screws.
 5. The implant of claim 4, wherein saideach of said at least one locking element forms an interference fit withsaid side surface of said respective one of said at least two bonescrews.
 6. The implant of claim 4, wherein said each of said at leastone locking element clamps onto said side surface of said respective oneof said at least two bone screws.
 7. The implant of claim 4, whereinsaid side surface of said head of said respective one of said at leasttwo bone screws has a height and said round cross section of said headof said respective one of said at least two bone screws is through amidpoint of said height, said round inner surface of said each of saidat least one locking element is adapted to contact said side surface ofsaid head of said respective one of said at least two bone screws atsaid midpoint.
 8. The implant of claim 1, wherein said respective one ofsaid at least two bone screws has a recess in said trailing end thereoffor engagement by a tool for rotation of said respective one of said atleast two bone screws, said each of said at least one locking elementhaving an opening through the center thereof, said recess having a firstcross sectional dimension transverse to the central longitudinal axis ofsaid respective one of said at least two bone screws, and said openinghaving a second cross sectional dimension transverse to the centrallongitudinal axis of said respective one of said at least two bonescrews when said each of said at least one locking element contacts saidrespective one of said at least two bone screws to retain saidrespective one of said at least two bone screws to said implant, saidfirst cross sectional dimension of said recess being less than saidsecond cross sectional dimension of said opening.
 9. The implant ofclaim 1, further in combination with a fusion promoting substance. 10.The implant of claim 9, wherein said fusion promoting substance is atleast in part other than bone.
 11. The implant of claim 9, wherein saidfusion promoting substance comprises bone morphogenetic protein.
 12. Theimplant of claim 1, wherein said bone contacting surface extends alongthe entire length of said body.
 13. The implant of claim 1, wherein atleast one of said bone screw receiving holes is configured to form aninterference fit with a properly dimensioned bone screw to be receivedtherein.
 14. The implant of claim 1, wherein at least a portion of oneof said implant, said locking element, and said bone screws is abioresorbable material.
 15. The implant of claim 1, wherein saidbone-contacting surface is textured for engagement of said body with theat least one bone.